how to choose element from list based on probabilities?

[Sidharthk]

Matthew Wilson <mwilson at sarcastic-horse.com> wrote in message news:<slrnbr81e4.gp0.mwilson at overlook.homelinux.net>...
> I have a list of very simple circle objects:
> 
> class Circle:
>     def __init__(self, x,y,r):
>         self.center =(x,y)
>         self.r = r
> 
> I want to write a function that accepts a list of circle objects and
> then chooses one of the circles and returns that circle.  The circles
> with the biggest areas should be the most likely to be chosen, but there
> should be some randomness.
> 
> Subsequent calls to the function should not return the same circle.
> 
> Can anyone help me out?

import random
import math
def getCircleMaker(circleList):
    circleList = list(circleList)
    circleList.sort(lambda a, b: cmp(b.r, a,r))
    def workerFunc():
        pos = int(random.randrange(len(circleList)**2)**0.5)
        return circleList.pop(pos)
    return workerFunc
        
        
        
circlelist = [Circle(0,0,random.randrange(100)) for e in range(100)]
            
getCircle =  getCircleMaker(circlelist)

and now just call getCircle() to get a circle

This is a very simple solution. getCircle will raise an IndexError
when the list finishes.
I havent really tried this but it should work in principle. :-)